Cocoa beans in their shells are conventionally processed at elevated temperatures until the shell detaches from the nibs. The shells are then cracked and separated from the nibs which are further processed in various ways to produce cocoa powder and chocolate products (see Fincke, H. “Handbuch der Kakaoerzeugnisse”, 2. Auflage 1965). The shells are considered as waste by-products for which several applications have been found.
US2011/0151098 provides a food comprising at least 30 mass % alkalized cocoa shells in the food and a method for manufacturing the corresponding food. However, this method does not comprise any washing steps or any removal of heavy metals.
EP2174555 discloses an acidified dairy food comprising cocoa shells, a method for its production, and the use of cocoa shells to increase the fibre content and/or the lower fat content of an acidified dairy product.
In United Kingdom patent application 2452972 a chocolate is described which incorporates cocoa beans with or without their shells.
EP1728434 discloses a process for extracting cocoa shells in order to produce fractions enriched in theobromine or in polyphenols.
European patent 1733624 relates to a process for milling cocoa shells without moving mechanical parts and to the granular edible products thereof. However, this invention as claimed performs a mere dry processing of cocoa shells and does not refer to any washing procedure or measures which are targeted on reducing the heavy metal concentration in cocoa shells.
Spanish patent ES 2099676 discloses a cocoa fibre product based on roasted cocoa husks and its application as a dietetic product in the pharmaceutical and food industry. However, no process parameters such as washing steps are mentioned.
GB patent 1195634 claims a flavouring and colouring extract from cocoa shells for use in confectionery and ice cream products.
In U.S. Pat. No. 4,156,030 there is a process described for preparing a berry-like flavourant and colorant by extracting cocoa shells with an acidified ethanol solution and by separating the resulting extract from the cocoa shell residue.
Furthermore, cocoa shells can be used inter alia for manufacturing paper (see http://www.blackmountainchocolate.com), for mulching (see www.ag-choice.com), for the manufacture of plastic products (see EP0784081A1) or of meat food packaging (see JP55064781A), as substitute for cork in linoleum (see Greenwood-Barton, L. H. Food Manufacture 1965; May: 52-56) or for cosmetics (see http://www.saag-ge.ch).
In the field of engineering sciences, several publications describe the use of cocoa shells as biofiltration support and for the removal of metals from contaminated soil and industrial effluents (see Meunier, N. et al. Bioresource Technology 2003; 90: 255-263).
For several decades it has been known that cocoa shells may contain undesirable components such as mycotoxins, heavy metals or pesticides which often pose a risk to human health (see “10 Jahre Katrin Janβen im LCI: Kakaoschalenforschung und Qualitätsmanagement”. Süsswaren 2009; 11-12). The majority of ochratoxin A in cocoa beans, e.g., is present in the cocoa shells and 98% of initial ochratoxin A contamination from cocoa beans can be removed by applying bicarbonate washing (see Amezqueta, S. et al. Alimentacion Equipos y Tecnologia 2009; 240: 38-42). Furthermore, due to their strong ion exchange properties cocoa shells significantly accumulate toxicologically relevant metal species such as aluminium (Al), lead (Pb), cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe) and nickel (Ni). Especially cocoa shells processed from cocoa beans of South American or Caribbean origin are remarkably contaminated by cadmium (see Matissek, R. und M. Raters. “Toxikologisch relevante Elemente in Kakao—Vorkommen und Risikobewertung”. Projekt Nr. 55. Stiftung der Deutschen Schokoladen-und Kakaowirtschaft. 2008).
Differently coloured cocoa-based food products may be prepared by alkalizing cocoa nibs, cocoa liquor or cocoa cake and cocoa powder, respectively. Whereas liquor alkalization potentially leads to degradation of cocoa butter and results in a narrow range of colour and flavour profiles, the alkalization of cocoa cake or cocoa powder may be accompanied by protein and starch degradation providing unfavourable effects on texture and taste of dairy food and confectionery. Although nib alkalization is regarded as best option for colour and flavour development in cocoa-based products, this process is more complex and cost-intensive due to the high commodity value of cocoa butter (see Dyer, B. 57th PCMA Production Conference 2003; 130-131; see Fischer, J. The Manufacturing Confectioner 2009; September: 89).
Alternatively, alkalized cocoa shell powder may be used to impart colouration in food products. Since cocoa shells on average contain only about 4 weight % of fatty components, the disadvantages associated with decomposition of cocoa butter can be avoided. EP2174557 discloses a food comprising at least 30 mass % alkalized cocoa shells as the only source of chocolate flavour in food products. However, this patent application is silent on processing of cocoa shells comprising the steps of sieving, grinding, washing, alkalizing and heavy metal removal.
Fat bloom in chocolate products is a major problem in the chocolate industry. “Bloom” in this context means a separation of fat crystals from the matrix of the chocolate, generally caused by separation of cocoa butter from the matrix and extrusion or recrystallization of fat to or on the surface with the result being white layering or splotches on the surface of the chocolate. Bloom is usually ascribed to partial liquification, e.g. due to temperature fluctuations, and then recrystallization of the fat which sometimes migrates to the surface. The bloom appears as a white, waxy substance on the surface of the chocolate and is objectionable to consumers.
Document JP2006271328A discloses an oil and fat composition containing a fat bloom preventing agent to be used for chocolate manufacture. The fat bloom preventing agent is selected from the group consisting of glycerol organic acid fatty acid ester, polyglyceryl saturated fatty acid ester, and sorbitan saturated fatty acid ester.
Japanese patent 2138937 claims a composition which can prevent fat bloom by using more than 20 weight % of a specific monounsaturated and disaturated triglyceride in which more than 75 weight % of the saturated groups is the residue of stearic acid.
U.S. Pat. No. 5,849,353 provides a process for preventing fat bloom in a chocolate-like product containing non-tempering cocoa butter substitute.
Chocolate fat bloom caused by a Form V to a Form VI transformation, whether or not this is also linked to fat migration, can be inhibited by the use of fats called “Prestine” with a very specific triglyceride composition (see Talbot, G. IFI 1995; 1: 40-45).